Monocrotaline presence in the Crotalaria (Fabaceae) plant genus and its influence on arthropods in agroecosystems

Abstract Crotalaria (Fabaceae) occurs abundantly in tropical and subtropical regions and has about 600 known species. These plants are widely used in agriculture, mainly as cover plants and green manures, in addition to their use in the management of phytonematodes. A striking feature of these species is the production of pyrrolizidine alkaloids (PAs), secondary allelochemicals involved in plant defense against herbivores. In Crotalaria species, monocrotaline is the predominant PA, which has many biological activities reported, including cytotoxicity, tumorigenicity, hepatotoxicity and neurotoxicity, with a wide range of ecological interactions. Thus, studies have sought to elucidate the effects of this compound to promote an increase in flora and fauna (mainly insects and nematodes) associated with agroecosystems, favoring the natural biological control. This review summarizes information about the monocrotaline, showing such effects in these environments, both above and below ground, and their potential use in pest management programs.

The Lambda Variant in Argentina: Analyzing the Evolution and Spread of SARS-CoV-2 Lineage C.37

The second wave of COVID-19 occurred in South America in early 2021 and was mainly driven by Gamma and Lambda variants. In this study, we aimed to describe the emergence and local genomic diversity of the SARS-CoV-2 Lambda variant in Argentina, from its initial entry into the country until its detection ceased. Molecular surveillance was conducted on 9356 samples from Argentina between October 2020 and April 2022, and sequencing, phylogenetic, and phylogeographic analyses were performed. Our findings revealed that the Lambda variant was first detected in Argentina in January 2021 and steadily increased in frequency until it peaked in April 2021, with continued detection throughout the year. Phylodynamic analyses showed that at least 18 introductions of the Lambda variant into the country occurred, with nine of them having evidence of onward local transmission. The spatial--temporal reconstruction showed that Argentine clades were associated with Lambda sequences from Latin America and suggested an initial diversification in the Metropolitan Area of Buenos Aires before spreading to other regions in Argentina. Genetic analyses of genome sequences allowed us to describe the mutational patterns of the Argentine Lambda sequences and detect the emergence of rare mutations in an immunocompromised patient. Our study highlights the importance of genomic surveillance in identifying the introduction and geographical distribution of the SARS-CoV-2 Lambda variant, as well as in monitoring the emergence of mutations that could be involved in the evolutionary leaps that characterize variants of concern.

Assessing the hidden diversity underlying consensus sequences of SARS-CoV-2 using VICOS, a novel bioinformatic pipeline for identification of mixed viral populations

INTRODUCTION

Coinfection with two SARS-CoV-2 viruses is still a very understudied phenomenon. Although next generation sequencing methods are very sensitive to detect heterogeneous viral populations in a sample, there is no standardized method for their characterization, so their clinical and epidemiological importance is unknown.

MATERIAL AND METHODS

We developed VICOS (Viral COinfection Surveillance), a new bioinformatic algorithm for variant calling, filtering and statistical analysis to identify samples suspected of being mixed SARS-CoV-2 populations from a large dataset in the framework of a community genomic surveillance. VICOS was used to detect SARS-CoV-2 coinfections in a dataset of 1,097 complete genomes collected between March 2020 and August 2021 in Argentina.

RESULTS

We detected 23 cases (2%) of SARS-CoV-2 coinfections. Detailed study of VICOS's results together with additional phylogenetic analysis revealed 3 cases of coinfections by two viruses of the same lineage, 2 cases by viruses of different genetic lineages, 13 were compatible with both coinfection and intra-host evolution, and 5 cases were likely a product of laboratory contamination.

DISCUSSION

Intra-sample viral diversity provides important information to understand the transmission dynamics of SARS-CoV-2. Advanced bioinformatics tools, such as VICOS, are a necessary resource to help unveil the hidden diversity of SARS-CoV-2.

POS0384 ULTRA SHORT ECHO TIME MRI (UTE) SEQUENCE IN THE ASSESSMENT OF INTERSTITIAL DISEASE IN PATIENTS WITH SYSTEMIC SCLEROSIS: CORRELATION WITH DISEASE EXTENSION AT CT AND WITH PULMONARY LUNG FUNCTION TESTS

Background

Interstitial lung disease (ILD) is the major cause of death in Systemic sclerosis (SSc). Computed tomography (CT) is the gold standard imaging technique to diagnose ILD and to assess ILD prognosis. ILD extent assessment at lung CT has shown to correlate with functional lung capacity: extensive lung disease (> 20%) correlate with significant lung capacity decline (forced vital capacity ((FVC) <70%) that is, in fact, associated with a higher mortality. Unfortunately, it is burdened by exposure to ionizing radiations that limits its use for the follow-up. For this reason, new MRI sequences were recently investigated, and Ultra Short Echo Time (UTE) emerged promising for ILD assessment.

Objectives

The aim of the study is to evaluate the reliability of an MRI-UTE sequence in the assessment of ILD extent in patients with SS in comparison with standard high-resolution CT images and to correlate the extension with pulmonary function tests (PFT).

Methods

Patients with SSc and ILD underwent a CT and UTE-MRI (1.5 T) acquisition on the same day. In the same week, they carried out PFT, with FVC and the diffusion capacity of carbon monoxide (DLCo) evaluation. Two thoracic radiologists assessed in consensus, on CT and UTE-MRI, the extent of ILD. Extensions were calculated as the mean percentage of lung involvement, evaluated at five levels, with an approximation of 5%. ILD extension were classified as limited (<20%) or extensive (> 20% or 20% with FVC <70%). The ANOVA test was adopted to compare the CT and MRI extensions of the ILD. Correlations of the extent of CT and UTE-MRI alterations with FVC and DLCo were calculated with Pearson’s correlation coefficient r. Sensitivity, Specificity, Positive Predictive Value (PPV) and Negative Predictive Value (VPN) of UTE-MRI were also calculated for UTE-MRI in determining ILD extension.

Results

The mean ILD extension was 20.9% in CT and 17.9 % in UTE-MRI (p-value=0.64). The correlation of ILD extension in CT with FVC and DLCo were significant (r=-0.66 (p<0.0001) and r=-0.59 (p<0.0008), respectively). The correlation of ILD extension in UTE-MRI with FVC and DLCo were significant (-0.68 (p<0.0001) and -0.57 (p<0.002), respectively) too. The UTE-MRI assessments agreed with CT in identifying limited or extensive ILD in 25/29 patients (19 limited and 6 extended) and discordant in 4 (1 limited and 3 extended to CT). UTE-MRI sensitivity and specificity in identifying extended ILD were high (86.4% (65.1% -97.1%) and 85.7% (42.1% -99.6%), respectively). PPV and NPV were 95.0% (75.4% -99.2%) and 66.7% (40.7% -85.7%), respectively.

Conclusion

UTE-MRI sequence, compared to CT, has shown high correlation with PFR and comparable ability in identifying patients with extensive ILD. Therefore, UTE-MRI seems new promising imaging sequence for the evaluation of ILD extension in SSc patients.

References

[1]Orlandi M, Landini N, Cerinic MM, Colagrande S. Pulmonary magnetic resonance imaging in systemic sclerosis: a jump in the future to unravel inflammation in interstitial lung disease. Clin Rheumatol. 2021 Sep;40(9):3461-3464. doi: 10.1007/s10067-021-05869-3. Epub 2021 Jul 30. PMID: 34328571.

[2]Romei C, Turturici L, Tavanti L, et al. The use of chest magnetic resonance imaging in interstitial lung disease: a systematic review. Eur Respir Rev. 2018;27(150):180062. Doi:10.1183/16000617.0062-2018

[3]Pinal-Fernandez I, Pineda-Sanchez V, Pallisa-Nuñez E, et al. Fast 1.5 T chest MRI for the assessment of interstitial lung disease extent secondary to systemic sclerosis. Clin Rheumatol. 2016;35(9):2339-2345. doi:10.1007/s10067-016-3267-0

Disclosure of Interests

None declared

POS1228 THE ROLE OF CHEST CT IN UNDERSTANDING INTERSTITIAL LUNG DISEASE (ILD): SYSTEMIC SCLEROSIS (SSc). VERSUS COVID-19

Background:

COVID-19 pandemic is a global emergency which may overlap on the clinical and radiological scenario of ILD in SSc. In clinical practice, the striking similarities observed at computed tomography (CT) between the diseases make it difficult to distinguish a COVID-19 superinfection from a progression of SSc-ILD.

Objectives:

The aim of our study was to identify the main CT features that may help distinguishing SSc-ILD from COVID-19 pneumonia.

Methods:

22 international readers were included and divided in the radiologist group (RAD) and non-radiologist group (nRAD). The RAD group included non-chest RAD and chest-RAD. A total of 99 patients, 52 with COVID-19 and 47 with SSc-ILD, were included in the study.

Results:

Fibrosis inside focal ground glass opacities (GGO) in the upper lobes; fibrosis in the lower lobe GGO; reticulations in lower lobes (especially if bilateral and symmetrical or associated with signs of fibrosis) were the CT parameters most frequently associated with SSc-ILD. The CT parameters most frequently associated with COVID- 19 pneumonia were: consolidation (CONS) in the lower lobes, CONS with peripheral (both central/peripheral or patchy distributions), anterior and posterior CONS and rounded-shaped GGOs in the lower lobes. After multivariate analysis, the presence of CONS in the lower lobes (p <0.0001) and signs of fibrosis in GGO in the lower lobes (p <0.0001) remained independently associated with COVID-19 pneumonia or SSc-ILD, respectively. These two variables were combined in a predictive score which resulted positively associated with the COVID-19 diagnosis, with 96.1% sensitivity and 83.3% specificity: 3 different risk class for COVID-19 pneumonia may be identified: high risk for COVID-19 pneumonia (5-9 points); probable overlap COVID-19 pneumonia in SSc-ILD (4 points); low risk for COVID-19 pneumonia (0-3 points).

Conclusion:

The CT differential diagnosis between COVID-19 Pneumonia and SSc-ILD is possible and may be fostered in practice by the use of a radiological score. In the case where an overlap of both diseases is suspected, the presence of consolidation in the lower lobes may suggest a COVID-19 pneumonia while the presence of fibrosis inside GGO may indicate a SSc-ILD.

References:

[1]Orlandi M, Landini N, Bruni C, et al. Infection or autoimmunity? The clinical challenge of interstitial lung disease in systemic sclerosis during COVID 19 pandemic. J Rheumatol. 2020 Dec 1: jrheum.200832

[2]Simpson S, Kay FU, Abbara S, et al. Radiological Society of North America Expert Consensus Statement on Reporting Chest CT Findings Related to COVID-19. Endorsed by the Society of Thoracic Radiology, the American College of Radiology, and RSNA [published online ahead of print, 2020 Apr 28]. J Thorac Imaging. 2020;10.1097/RTI.0000000000000524.

[3]Cheng C, Li C, Zhao T, et al. COVID-19 with rheumatic diseases: a report of 5 cases. Clin Rheumatol. 2020;39(7):2025-2029.

[4]Mariano RZ, Rio APTD, Reis F. Covid-19 overlapping with systemic sclerosis. Rev Soc Bras Med Trop. 2020 Sep 21;53:e20200450.

Disclosure of Interests:

None declared

POS0264 THE EMERGING ROLE OF MAGNETIC RESONANCE IMAGING IN INTERSTITIAL LUNG DISEASE IN SYSTEMIC SCLEROSIS: EVIDENCE FOR ULTRA SHORT TE AND COMPRESSED SENSING VIBE ACQUISITIONS AS PROMISING TOOLS FOR THE EVALUATION OF PARENCHYMAL ALTERATIONS

Background:

Interstitial lung disease (ILD) is a frequent complication and the major cause of death in Systemic sclerosis (SSc). Computed tomography (CT) is the gold standard imaging technique to assess ILD but is burdened by exposure to ionizing radiations that limits its use for the follow-up. MRI sequences with Ultra Short Echo Time (UTE) are promising for ILD.

Objectives:

We tested two MRI sequences, UTE Spiral VIBE and Compressing Sensing (CS) VIBE, in SSc-ILD, in comparison to chest CT.

Methods:

SSc patients with suspected-ascertained ILD were evaluated for undergoing CT-MRI examinations in the same day. Two radiologists visually scored the extent of ground glass opacities (GGO), reticulations, honeycombing and consolidations on CT-MRI. The sum of alteration was assumed as ILD extent. A quantitative texture analysis (qCT) was also performed on CT. Cohen’s k was adopted for interreader concordance in ILD detection. MRI sensitivity and specificity in ILD detection were evaluated. Lin’s concordance was adopted to compare extent analysis between readers and between CT (visual and qCT analysis) and MRI sequences.

Results:

54 patients performed both CT and MRI. MRI interreader concordance was moderate in ILD detection, while ILD and GGO extent analysis showed good or very good concordance. UTE Spiral VIBE had a sensitivity and specificity in ILD detection of 95.8% and 77.8%, while alterations extent analysis obtained a very good concordance with CT for ILD and GGO. CS VIBE showed a sensitivity and specificity in ILD detection of 46.7% and 95.0%, but a slight or fair concordance with CT in all alterations’ extent analysis.

Conclusion:

MRI UTE Spiral VIBE sequences are helpful in the evaluation of SSc-ILD. Larger cohorts of patients will be needed to confirm that MRI may be useful in clinical practice, reducing the radiological load of chest CT

References:

[1]Romei C, Turturici L, Tavanti L, et al. The use of chest magnetic resonance imaging in interstitial lung disease: a systematic review. Eur Respir Rev. 2018;27(150):180062. Doi:10.1183/16000617.0062-2018

[2]Miller GW, Mugler JP, Sá RC, Altes TA, Prisk GK, Hopkins SR. Advances in functional and structural imaging of the human lung using proton MRI. NMR Biomed. 2014;27(12):1542-1556. doi:10.1002/nbm.3156

[3]Pinal-Fernandez I, Pineda-Sanchez V, Pallisa-Nuñez E, et al. Fast 1.5 T chest MRI for the assessment of interstitial lung disease extent secondary to systemic sclerosis. Clin Rheumatol. 2016;35(9):2339-2345. doi:10.1007/s10067-016-3267-0

[4]Ohno Y, Koyama H, Yoshikawa T, et al. Pulmonary high-resolution ultrashort TE MR imaging: Comparison with thin-section standard- and low-dose computed tomography for the assessment of pulmonary parenchyma diseases: Pulmonary MRI with UTE in Pulmonary Disease. J Magn Reson Imaging. 2016;43(2):512-532. doi:10.1002/jmri.25008

Disclosure of Interests:

None declared

CT volume of enhancement of disease (VED) can predict the early response to treatment and overall survival in patients with advanced HCC treated with sorafenib

OBJECTIVES

To analyse the predictive value of the volume of enhancement of disease (VED), based on the CT arterial enhancement coefficient (ΔArt%), in the evaluation of the sorafenib response in patients with advanced hepatocellular carcinoma (HCC).

METHODS

Patients with sorafenib-treated advanced HCC, who underwent a multiphase contrast-enhanced CT before (T0) and after 60-70 days of starting therapy (T1), were included. The same target lesions utilised for the response evaluation according to modified Response Evaluation Criteria in Solid Tumors criteria were retrospectively used for the ΔArt% calculation ([(HUarterial phase - HUunenhanced phase) / HUunenhanced phase] × 100). ΔArt% was weighted for the lesion volume to obtain the VED. We compared VEDT0 and VEDT1 values in patients with clinical benefit (CB) or progressive disease (PD). The impact of VED, ancillary imaging findings, and blood chemistries on survival probability was evaluated.

RESULTS

Thirty-two patients (25 men, mean age 65.8 years) analysed between 2012 and 2016 were selected. At T1, 8 patients had CB and 24 had PD. VEDT0 was > 70% in 8/8 CB patients compared with 12/24 PD patients (p = 0.011). Patients with VEDT0 > 70% showed a significantly higher median survival than those with lower VEDT0 (451.5 days vs. 209.5 days, p = 0.032). Patients with VEDT0 > 70% and alpha-fetoproteinT0 ≤ 400 ng/ml had significantly longer survival than all other three combinations. In multivariate analysis, VEDT0 > 70% emerged as the only factor independently associated with survival (p = 0.037).

CONCLUSION

In patients with advanced HCC treated with sorafenib, VED is a novel radiologic parameter obtained by contrast-enhanced CT, which could be helpful in selecting patients who are more likely to respond to sorafenib, and with a longer survival.

KEY POINTS

• To achieve the best results of treatment with sorafenib in advanced HCC, a strict selection of patients is needed. • New radiologic parameters predictive of the response to sorafenib would be essential. • Volume of enhancement of disease (VED) is a novel radiologic parameter obtained by contrast-enhanced CT, which could be helpful in selecting patients who are more likely to respond to therapy, and with a longer survival.

Description of the immatures of Scaptocoris carvalhoi Becker (Hemiptera: Cydnidae)

Nymphs and adults of the burrower bug Scaptocoris carvalhoi Becker feed on vegetal sap of their host plants through the roots, and little is known on the morphology and biology of its immature stage. Therefore, we aimed to characterize the immatures of S. carvalhoi by describing the egg and the morphology of each instar. Eggs of S. carvalhoi have a smooth chorion surface without visible micropylar processes. The presence of five instars was confirmed by the coefficient of determination (R (2) > 0.95) and by the growth constant (K between 1.2 and 1.6). Nymphs have an elliptical body and fossorial scythe-like forelegs. The tarsi are absent as in adults, and the prototarsal insertion region becomes visible only in the fourth instar. Nymphs from first to fourth instar of S. carvalhoi showed the presence of 1 + 1 trichobothria in urosternites III to VII, close to the anterior margin and inside the spiracles; besides these trichobothria, fifth instars presented 1 + 1 pre-trichobothria in urosternites III to V located posteriorly, almost in the row of spiracles close to the posterior margin of the urosternites. This is the first detailed morphological record of immatures belonging to Scaptocoris.

The carbohydrate-binding module of Fragaria × ananassa expansin 2 (CBM-FaExp2) binds to cell wall polysaccharides and decreases cell wall enzyme activities "in vitro"

A putative carbohydrate binding module (CBM) from strawberry (Fragaria × ananassa Duch.) expansin 2 (CBM-FaExp2) was cloned and the encoding protein was over-expressed in Escherichia coli and purified in order to evaluate its capacity to bind different cell wall polysaccharides "in vitro". The protein CBM-FaExp2 bound to microcrystalline cellulose, xylan and pectin with different affinities (K(ad) = 33.6 ± 0.44 mL g(-1), K(ad) = 11.37 ± 0.87 mL g(-1), K(ad) = 10.4 ± 0.19 mL g(-1), respectively). According to "in vitro" enzyme assays, this CBM is able to decrease the activity of cell wall degrading enzymes such as polygalacturonase, endo-glucanase, pectinase and xylanase, probably because the binding of CBM-FaExp2 to the different substrates interferes with enzyme activity. The results suggest that expansins would bind not only cellulose but also a wide range of cell wall polymers.

Mating behavior of Diabrotica speciosa (Coleoptera: Chrysomelidae)

Diabrotica speciosa (Germar) is an economically important pest of Neotropical cultures and represents a quarantine risk for Neartic and Paleartic Regions. Despite its agricultural importance, few studies have been done on mating behavior and chemical communication, which has delayed the development of behavioral techniques for population management, such as the use of pheromone traps. In this study, we determined 1) the age at first mating; 2) diel rhythm of matings; 3) number of matings over 7 d; 4) the sequence of D. speciosa activities during premating, mating, and postmating; 5) the duration of each activity; and 6) response to male and female conspecific volatiles in Y-tube olfactometer. The first mating occurred between the third and seventh day after adult emergence and the majority of pairs mated on the fourth day after emergence. Pairs of D. speciosa showed a daily rhythm of mating with greater sexual activity between the end of the photophase and the first half of the scotophase. During the 7 d of observation, most pairs mated only once, although 30% mated two, three, or four times. In a Y-tube olfactometer, males were attracted by virgin females as well as by the volatile compounds emitted by females. Neither males nor their volatiles were attractive to either sex. Our observation provide information about mating behavior of D. speciosa, which will be useful in future research in chemical communication, such as identification of the pheromone and development of management techniques for this species using pheromone traps.

MR-diffusion imaging in assessing chronic liver diseases: does a clinical role exist?

PURPOSE

This study was done to evaluate whether and which of the magnetic resonance diffusion-weighted imaging (MR-DWI) parameters - apparent diffusion coefficient (ADC), diffusion (D) or perfusion fraction (f) - correlates with the degree of chronic liver disease progression.

MATERIALS AND METHODS

Twenty-eight patients were evaluated with abdominal MR-DWI from March to November 2010: seven healthy volunteers, seven patients with chronic liver disease F0-F2 (METAVIR score), seven F3-F4 Child-Pugh A, and seven F4 Child-Pugh BC, classified as groups 1-4, respectively. DWI acquisitions were performed during breath-holding (b = 0-150 s/mm(2) and 1,000) and free breathing (multi-b = 0-200-400-600-800-1,000 s/mm(2)). Using a double-blind control procedure, two observers estimated ADC, D, and f by applying a region of interest (ROI) in 4/12 sections in the middle-lower portion of the right hepatic lobe. Statistical analysis was done with analysis of variance (ANOVA).

RESULTS

A reduction in the mean value of f, ADC(150) and, to a lesser extent, ADC(1,000) is shown to progress from healthy volunteers (group 1) to cirrhosis patients (group 4), with wide overlap among groups. There were no statistically significant changes of D.

CONCLUSIONS

Our results indicate that stratifying patients with chronic liver disease for clinical purposes cannot be done with DWI. However, there is a tendency among groups for reduced perfusion-related parameters as chronic liver disease progresses.

Early left ventricular mechanics abnormalities in prehypertension: a two-dimensional strain echocardiography study

BACKGROUND

Prehypertension predicts established hypertension. In this study, the aim was to analyze left ventricular (LV) mechanics in borderline prehypertensive (pre-HT) and hypertensive (HT) subjects through two-dimensional (2D)-strain echocardiography and then evaluate possible relations between cardiac parameters and insulin metabolism (homeostasis model assessment of insulin resistance (HOMA(IR)).

METHODS

Seventy-four consecutive newly diagnosed, untreated HT were divided, on the basis of their office blood pressure (BP) measurements, confirmed by ambulatory BP monitoring (ABPM), in 41 borderline pre-HT (ABPM: 122.5 +/- 6.7/76.2 +/- 5.2 mm Hg) and 33 never-treated mild HT (ABPM: 138.3 +/- 7.3/87.6 +/- 7.1 mm Hg). Thirty-three healthy normotensive (NT) controls (ABPM: 114.8 +/- 6.3/73.1 +/- 6.1 mm Hg) (P < 0.0001) were also studied (NT). All subjects performed 2D color Doppler and pulsed-wave tissue Doppler imaging (PW-TDI).

RESULTS

Left ventricular mass (LVM) was significantly higher in pre-HT (39.2 +/- 8.7 g/m(2.7)) and in HT (43.6 +/- 8.5 g/m(2.7)) compared with NT (30.9 +/- 7.4 g/m(2.7)) (P < 0.0001). A mild LV diastolic dysfunction was found both with Doppler mitral flow velocity and PW-TDI at mitral annulus level analysis. Longitudinal 2D strain in pre-HT (-18.9% +/- 3.4) and in HT (-18.0% +/- 3.3) was significantly lower than in NT (-23.9% +/- 3.0) (P < 0.002). These LV abnormalities were associated with systolic ABPM, LVM, and HOMA(IR).

CONCLUSIONS

Early abnormalities of LV longitudinal systolic deformation were found both in pre-HT and HT, together with a mild LV diastolic dysfunction. In both groups this early cardiac systolic and diastolic dysfunction is associated to insulin resistance, systolic pressure load, and cardiac remodeling.

Relationship between preclinical abnormalities of global and regional left ventricular function and insulin resistance in severe obesity: a Color Doppler Imaging Study

BACKGROUND

The aim of this study was to evaluate the relationship between insulin resistance and preclinical abnormalities of the left ventricular structure and function detected in severe obesity by Color Doppler Myocardial Imaging (CDMI). Forty-eight consecutive severely obese patients (Group O) (11 males, 37 females, mean age 32.8+/-7 years) were enrolled. Forty-eight sex- and age-matched non-obese healthy subjects were also recruited as controls (Group C). All subjects underwent conventional 2D-Color Doppler echocardiography and CDMI. The homeostasis model assessment insulin resistance index (HOMA-IR) was used to assess insulin resistance results. Obese subjects had a greater left ventricular mass index (by height) (58.8+/-14 g/m(2.7)) than controls (37+/-8 g/m(2.7)) (P<0.0001), owing to compensation response to volume overload caused by a greater cardiac output (P<0.02). Preload reserve was increased in obese subjects, as demonstrated by a significant increase in left atrial dimension (P<0.0001). Obese patients had a slightly reduced LV diastolic function (transmitral E/A ratio: Group O, 1.1+/-0.8 vs Group C, 1.5 +/-0.5; P<0.002). Cardiac deformation assessed by regional myocardial systolic strain and strain rate (SR) values was significantly lower (abnormal) in obese patients than in controls, both at the septum and lateral wall level. These strain and SR abnormalities were significantly related to body mass index. In addition, the early phase of diastolic function, evaluated using SR, was compromised in obese patients (P<0.001). The HOMA-IR values in obese patients were significantly higher (3.09+/-1.6) than those determined in the control group (0.92+/-0.5) (P<0.0001). The HOMA-IR values, in the obese group, were significantly related to systolic strain and SR values sampled at the septum level (P<0.0001).

CONCLUSION

In conclusion, this study has demonstrated that obese patients pointed out systolic structural and functional abnormalities at a preclinical stage, in particular through strain and SR analysis; on the other hand, those altered CDMI parameters well distinguish obese subjects as compared with the control group. Furthermore, another main finding of the study was that myocardial deformation (systolic strain) could have a correlation with insulin resistance level.

Ultrastructural ciliary findings in nasal obstructive diseases

Specific ultrastructural findings have widely been described in case of obstructive nasal diseases due to congenital defects. Ciliary impairment has in particular been observed as the main pathological feature in these conditions. In this study, nasal mucosal samples from different pathologies have been collected via the "brushing" technique and analysed by transmission electron microscopy. TEM analysis was focused on specific features, such as the numerical array of peripheral and central doublets of the cilium axoneme, including eventual microtubular disarrangement; partial or total loss of inner and/or outer dynein arms; defects of radial spokes and nexin links; disorientation of the ciliary axis in closely adjacent cilia, calculating the angle between the line crossing the central microtubular core and the horizontal ciliary axis and compound cilia (CC). Statistical comparison was carried out between study and control groups. A significant incidence of organic ciliary defects was found not only in patients with inflammatory processes, but mostly in those supposed to have a long-lasting nasal respiratory disease due to mechanical stenosis in relation to septum deviation and turbinate hypertrophy. Prevalence and percentage of compound cilia were instead more related to inflammatory conditions. The "brushing" technique can be considered an easy and reliable method for the assessment of the condition of the nasal mucosa. According to the findings derived from this study, mechanical nasal obstruction seems to cause major alterations on the nasal ciliary arrangement, thus determining a functional impairment on the whole nasal function.

Coronary microcirculation into different models of left ventricular hypertrophy-hypertensive and athlete's heart: a contrast echocardiographic study

The study was carried out in two different models of left ventricular hypertrophy: athlete's heart and essential arterial hypertension. Three groups of strictly age-matched males were studied: one group of 10 young adult untreated essential hypertensive patients (H), a second group of 10 athletes (A), and a group of 10 healthy individuals as controls (C). A Sonos 5500 echograph with S4 harmonic transducer was used with Levovist (ultrasonic tracer) before and after dipyridamole injection; digitised images of quantitative myocardial contrast echocardiography were collected with Power Harmonic Doppler. Angio images were analysed using dedicated PC software by placing a region-of-interest on the septum. Peak intensity, half-time (HT), the area under the curve of appearance and disappearance of microbubbles at 2/3 of PI, both in absolute and indexed values (/LVMi), were sampled. The per cent increase of PI after dipyridamole was significantly higher in C (+73%, P < 0.01) than in H (+31%) and in A (+33%) (P < 0.05). The area of appearance was significantly lower in H in comparison with C and A, both at rest and after vasodilatation. The disappearance area after dipyridamole was significantly higher in C and in A (+124%) than in H (+104%) (P < 0.05). Some hypothesis could be made: an impairment in the coronary microcirculatory function in hypertensive patients could be because of an in-crease in the arteriolar resistance. Angiogenesis and several different functional adaptations are the mechanisms that allow an optimal distribution of oxygen and of substrates to the hypertrophied myocardium of the athletes.

Effects of abciximab on microvascular integrity and left ventricular functional recovery in patients with acute infarction treated by primary coronary angioplasty

AIM

To investigate the effect of abciximab on microvascular integrity and left ventricular (LV) functional recovery in patients with acute myocardial infarction (MI) treated by primary coronary angioplasty (PTCA).

METHODS AND RESULTS

Thirty-one patients (27 males; age 39-76 years) with first, acute MI (<6 h after onset) were randomized to receive either abciximab+primary PTCA (n=17) or primary PTCA alone (n=14). Baseline characteristics of the two groups were similar. Myocardial reperfusion was studied shortly after PTCA by corrected TIMI frame count (cTFC) and intracoronary myocardial contrast echocardiography (MCE), after 48 h by intravenous MCE using intermittent, harmonic power Doppler, and after 1 month by intravenous MCE and 99 mTc-tetrofosmin SPECT. The patients treated with abciximab showed a shorter cTFC (23+/-4 vs 30+/-9 frames; P<0.05), a more preserved microvascular integrity shortly after PTCA (77% vs 55%; P<0.01), after 48 h (86% vs 50%; P<0.005) and at 1-month follow-up (86% vs 54% by MCE, P<0.001, and 68% vs 60% by SPECT, P<0.005) than patients treated with PTCA alone. Abciximab patients also showed a better recovery of LV function, as demonstrated by greater reduction in wall motion score index (1.4+/-0.3 vs 1.5+/-0.2; P<0.05) and increase in LV ejection fraction (53+/-7% vs 48+/-5%; P<0.001).

CONCLUSIONS

Abciximab improves microvascular perfusion and LV functional recovery in primary PTCA.

Coronary microcirculation in essential hypertension: a quantitative myocardial contrast echocardiographic approach

AIMS

The aims of the present study were: (a) to demonstrate whether quantitative myocardial contrast echocardiography can detect the increase in coronary flow induced by dipyridamole infusion vasodilation through the myocardial opacification due to the transit of microbubbles, both at rest and after dipyridamole induced vasodilation; (b) to explore the coronary microcirculatory function before and after dipyridamole in two different models: asymptomatic and relatively young hypertensive patients with a mild degree of left ventricular hypertrophy, and healthy controls.

METHODS AND RESULTS

Two groups of strictly age-matched males were studied (case-control study): 10, relatively young and asymptomatic essential hypertensive patients with a mild degree of left ventricular hypertrophy with a normal left ventricular function, and 10 healthy controls. The main findings were: the microbubbles' appearance area was significantly lower in hypertensive patients than in controls (P<0.05) because of a significantly lower time to peak. The peak intensity at rest was higher in hypertensives than in controls (P<0.05); but the per cent increase after vasodilatory stimulus was significantly higher in controls (+71% in controls vs +31% in hypertensives; P<0.05). The microbubbles' disappearance area was comparable in both groups at rest; the per cent increase of this parameter after dipyridamole was significantly higher in controls (+124%) than in hypertensives (+90%) (P<0.05). The results achieved in this study documented that the coronary microcirculation in hypertensive patients presenting a mild degree of left ventricular hypertrophy, explored with quantitative myocardial contrast echocardiography, showed a different behaviour in comparison with controls, in the vasodilatory response to dipyridamole.

CONCLUSION

The coronary microcirculation in hypertensives showed a reduced vasodilation capacity of the resistance arterioles under dipyridamole induced vasodilatation, and a possible impairment of the endothelium dependent vasodilation. This happened despite an increase in the left ventricular mass, where the relation between capillary bed distribution and hypertrophied myocardium (rarefaction phenomenon) is not completely respected.

Hemodynamic performance of stented and stentless aortic bioprostheses

BACKGROUND

This study compares the hemodynamic performance of stented and stentless bioprostheses used for aortic valve replacement in patients with aortic stenosis and small aortic root.

METHODS

Between 1995 and 1998, 37 patients with a 21-mm aortic annulus (group 1) underwent aortic valve replacement with either a 21-mm Edwards Perimount or a 23-mm St. Jude Toronto bioprosthesis whereas 47 patients with a 23-mm aortic annulus (group 2) received either a 23-mm Medtronic Mosaic or a 25-mm Edwards Prima bioprosthesis. In each group mean and peak gradients, effective orifice area index, and left ventricular mass index were compared during follow-up.

RESULTS

Group 1 patients showed a significant reduction of mean (p < 0.001) and peak gradients (p = 0.001) during follow-up, more evident for St. Jude Toronto versus Edwards Perimount (p = 0.02 and p = 0.05, respectively). Group 2 patients showed a significant reduction of mean and peak gradients (p < 0.001), more evident for Edwards Prima versus Medtronic Mosaic (p < 0.001 and p = 0.07, respectively). Effective orifice area index significantly increased only in group 1 (p = 0.005). Left ventricular mass index significantly decreased in all patients regardless of the type of valve (p < 0.001). Patients with Edwards Prima showed a trend to a higher regression of left ventricular mass index versus Medtronic Mosaic recipients (p = 0.07).

CONCLUSIONS

After aortic valve replacement, stented and stentless bioprostheses exhibited similar results with a more evident hemodynamic improvement during follow-up in the stentless valves. Stented bioprostheses of new generation, however, may parallel the hemodynamic performance of stentless valves and appear to be a valid alternative for aortic valve replacement in elderly patients with a small aortic annulus.

Dissection of atrial septum after mitral valve replacement

We report a patient who presented with paraprosthetic leak complicated by dissection of the interatrial septum after mitral valve replacement. A review of the literature provides confirmation that only 3 cases have been previously reported of this potential, albeit extremely rare, complication of prosthetic mitral valve replacement. Prosthesis oversizing and improper mitral annular handling appeared to be the predisposing factors of this complication.

Hemodynamic assessment of the Medtronic Mosaic bioprosthesis in the aortic position

BACKGROUND AND AIM OF THE STUDY

The Medtronic Mosaic bioprosthesis (MMB) is a newly developed tissue valve which incorporates several features such as a low-profile semi-flexible stent, zero-pressure tissue fixation, and anti-mineralization pretreatment with alpha-amino oleic acid aimed to improve hemodynamics and prevent structural deterioration.

METHODS

Between November 1995 to June 1999, 62 patients underwent aortic valve replacement (AVR) with the MMB; 41 of these who reached the one-year follow up interval and who had isolated AVR without any concomitant procedure with size 23 mm and 25 mm MMB were evaluated by serial echocardiography after three, six and 12 months.

RESULTS

For size 23 mm valves, mean and peak gradients were 12+/-3 and 21+/-6 mmHg at 3 months, 12+/-3 and 20+/-5 mmHg at 6 months, and 12+/-4 and 20+/-6 mmHg at 12 months. For size 25 mm valves, mean and peak gradients were 13+/-2 and 22+/-4 mmHg at 3 months, 12+/-3 and 21+/-5 mmHg at 6 months, and 12+/-4 and 22+/-6 mmHg at 12 months. In patients with 23 mm MMB, left ventricular mass index (LVMi) was reduced from 181+/-34 g/m2 before surgery to 158+/-32, 150+/-28 and 140+/-25 g/m2 at 3, 6 and 12 months after AVR (p <0.001); in patients with 25 mm MMB, LVMi was reduced from 182+/-28 g/m2 before surgery to 165+/-25, 156+/-24 and 146+/-19 g/m2 at 3, 6 and 12 months after AVR (p <0.001).

CONCLUSION

Our results indicate that MMB is associated with low mean and peak gradients and significant reduction in LVMi throughout the postoperative period. Thus, the MMB appears to be an excellent cardiac valve substitute in elderly subjects who require AVR.

Mitral valve annuloplasty for degenerative disease: assessment of four different techniques

BACKGROUND AND AIM OF THE STUDY

Mitral valve repair (MVR) is the treatment of choice in patients with degenerative valve disease. However, controversy persists as to whether mitral valve annuloplasty should always be included as part of the reconstructive procedure.

METHODS

The records of 62 consecutive patients undergoing MVR for degenerative disease between January 1994 and December 1996 were reviewed. Four different annuloplasty techniques were associated with various MVR procedures: local posterior annuloplasty (group 1, n = 10), rigid Carpentier ring (group 2, n = 20), Duran ring (group 3, n = 17), and posterior annular plication with autologous pericardium (group 4, n = 15). The four patient groups were similar in terms of preoperative clinical and echocardiographic characteristics. Serial clinical and echocardiographic follow up was performed to assess functional status and stability of repair.

RESULTS

There were no early or late deaths. Mean follow up in the entire patient series was 31 +/- 12 months. One patient in group 2 required reoperation 14 months after MVR. In all groups there was a significant improvement in NYHA functional class (from 2.7 +/- 0.6 to 0.9 +/- 0.5, p <0.001), with a reduction of left ventricular end-diastolic and end-systolic volumes (154 +/- 50 ml to 105 +/- 33 ml, p <0.001; and 64 +/- 23 ml to 52 +/- 22 ml, p <0.001). In patients of groups 2, 3 and 4, residual mitral incompetence at follow up (0.8 +/- 0.9 in group 2, 0.8 +/- 0.7 in group 3, and 0.2 +/- 0.6 in group 4) was not significantly different from discharge. However, in group 1, a higher degree of residual mitral regurgitation was present at discharge (0.9 +/- 0.6) with a trend to progress at follow up (1.6 +/- 0.5).

CONCLUSION

In patients with degenerative mitral valve disease, MVR provides clinical and functional improvement. Techniques of stabilization of the entire posterior mitral annulus achieve better early and medium-term results, and should be always considered as part of MVR. Autologous pericardium appears to be an excellent annuloplasty material, though its apparent superiority over synthetic rings must be confirmed at longer follow up.

Performance of 21-mm size perimount aortic bioprosthesis in the elderly

BACKGROUND

Aortic valve replacement in elderly patients with a small aortic annulus may pose difficult problems in terms of prosthesis selection. We have evaluated the hemodynamic performance of the 21-mm Carpentier-Edwards Perimount bioprosthesis implanted in elderly patients.

METHODS

From July 1996 to June 1998, 19 patients (17 women and 2 men, mean age 76+/-4 years and mean body surface area 1.73+/-0.13 m2), had aortic valve replacement with a 21-mm Carpentier-Edwards Perimount bioprosthesis. The hemodynamic performance of the valve was evaluated in 16 patients, who completed at least a 6-month follow-up interval, with transthoracic color-Doppler echocardiography with particular reference to peak and mean transprosthetic gradients, effective orifice area index, and regression of left ventricular mass index.

RESULTS

There were no late deaths and no major postoperative complications. At a mean follow-up of 12+/-7 months, compared to discharge, all patients showed clinical improvement with a significant reduction of peak gradient (from 23+/-4 to 21+/-6 mm Hg, p = 0.04) and left ventricular mass index (from 181+/-23 to 153+/-20 g/m2; p<0.001), whereas mean gradient (from 13+/-3 to 13+/-4 mm Hg, p = not significant) and effective orifice area index (from 1.12+/-0.34 to 1.13+/-0.28 cm2/m2, p = not significant) remained substantially unchanged.

CONCLUSIONS

The use of a 21-mm Carpentier-Edwards Perimount bioprosthesis is associated with low transprosthetic gradients and significant reduction in left ventricular hypertrophy after aortic valve replacement. The results of our study suggest that a 21-m Carpentier-Edwards Perimount bioprosthesis should be considered a valid option in elderly patients with aortic valve disease and a small aortic annulus.

The Edwards Prima stentless valve: hemodynamic performance at one year

BACKGROUND

The Edwards Prima stentless valve (EPSV) is a porcine aortic root cylinder with resected coronary ostia, fixed in glutaraldehyde at low pressure. The purpose of this study was to evaluate the hemodynamic performance of the EPSV 1 year after aortic valve replacement.

METHODS

From December 1994 to February 1996, 29 patients underwent aortic valve replacement with EPSV used in the subcoronary position (group 1, n = 23) or as a root replacement (group 2, n = 6). Hemodynamic performance of EPSV was assessed by two-dimensional Doppler echocardiography at 1 week, 6 months, and 1 year by calculating peak transprosthetic velocity, peak and mean gradients, effective orifice area, degree of aortic regurgitation, and regression of left ventricular hypertrophy.

RESULTS

There were no operative deaths. One patient in group 2 died after 3 months at reoperation for endocarditis. In group 1 early mean gradient (25+/-5 mm Hg for 23 mm and 19+/-5 mm Hg for 25 mm) decreased at 6 months and 1 year in the 23-mm size (17+/-7 mm Hg and 15+/-4 mm Hg, p < 0.01) and at 1 year in the 25-mm size (14+/-4 mm Hg, p = 0.03) without modifications of the effective orifice area in both sizes. A significant reduction in left ventricular hypertrophy occurred at 6 months and 1 year in both sizes. In group 2 lower early gradients were recorded with subsequent improvement at follow-up; reduction in left ventricular hypertrophy occurred as well.

CONCLUSIONS

The EPSV used in the subcoronary position has shown high early gradients, which partially regressed at 6 months, with further improvement at 1 year. Gradients are attributed to inward folding of the Dacron cloth at the right coronary ostium, being more evident in patients with aortic stenosis without dilatation of the aortic root and coronary ostia close to the annulus. In such patients a better early hemodynamic result can be obtained by using the EPSV as a root replacement.

Prospective evaluation of frequency and nature of transcranial high-intensity Doppler signals in prosthetic valve recipients

BACKGROUND AND AIM OF THE STUDY

In asymptomatic prosthetic valve recipients, high-intensity transient signals (HITS) observed with transcranial Doppler (TCD) are a phenomenon of obscure clinical relevance which nature has not yet been elucidated convincingly.

METHODS

Eighty-three patients without carotid disease, history of cerebrovascular accidents, and with negative preoperative TCD undergoing either valve replacement (mitral, n = 11; aortic, n = 56; mitral + aortic, n = 6; 40 mechanical prostheses, 29 biological prostheses, 10 homografts) or mitral repair (n = 10) were evaluated prospectively by means of TCD at discharge, three months and one year after surgery, to analyze the presence, incidence and characteristics of HITS. Furthermore, in 12 patients positive for HITS, TCD was repeated during a 30-min period of 100% O2 inhalation.

RESULTS

Twenty-five patients (30%) were positive for HITS at all postoperative controls, although no neurological symptoms were observed. Mechanical prostheses showed a significantly higher incidence of HITS (85%) than biological prostheses (10%, p <0.001), repaired mitral valves (0%, p <0.001) and homografts (0%, p <0.001). At multivariate analysis the presence of a mechanical prosthesis was the only significant predictor of detection of HITS after valve replacement. During O2 inhalation, a significant decrease in the number of HITS per hour (55 +/- 79 versus 22 +/- 31, p = 0.002) occurred, which returned to initial values when room-air breathing was resumed.

CONCLUSIONS

Prosthetic valve replacement, particularly when mechanical devices are used, is associated with the generation of HITS which persist throughout the follow up period, but remain clinically silent. The decrease of HITS during O2 inhalation strongly supports the hypothesis of the gaseous nature of such signals and confirms the validity of this method in helping to differentiate gaseous microemboli from solid microemboli in prosthetic valve recipients.

Combined mitral and tricuspid valve repair in acute infective endocarditis

Combined repair of the mitral and tricuspid valves involved with acute infective endocarditis was carried out in a 38-year-old drug addict. Mitral valve repair included vegetectomy, closure of posterior leaflet perforation, and posterior annuloplasty with a patch and a strip of glutaraldehyde-tanned autologous pericardium, respectively, while the tricuspid valve was reconstructed with the use of artificial chordae and valve bicuspidalization. At five months follow up the patient is asymptomatic, with echocardiographic evidence of only trivial mitral and tricuspid incompetence, and no signs of recurrent infection. This case report supports the use of valve reconstruction as a valuable option in patients in whom there is simultaneous involvement of the mitral and tricuspid valves with infective endocarditis.

Modulation of hepatitis C virus NS3 protease and helicase activities through the interaction with NS4A

The hepatitis C virus nonstructural 3 protein (NS3) possesses a serine protease activity in the N-terminal one-third, whereas RNA-stimulated NTPase and helicase activities reside in the C-terminal portion. The serine protease activity is required for proteolytic processing at the NS3-NS4A, NS4A-NS4B, NS4B-NS5A, and NS5A-NS5B polyprotein cleavage sites. NS3 forms a complex with NS4A, a 54-residue polypeptide that was shown to act as an essential cofactor of the NS3 protease. We have expressed in Escherichia coli the NS3-NS4A precursor; cleavage at the junction between NS3 and NS4A occurs during expression in the bacteria cells, resulting in the formation of a soluble noncovalent complex with a sub-nanomolar dissociation constant. We have assessed the minimal ionic strength and detergent and glycerol concentrations required for maximal proteolytic activity and stability of the purified NS3-NS4A complex. Using a peptide substrate derived from the NS5A-NS5B junction, the catalytic efficiency (kcat/Km) of NS3-NS4A-associated protease under optimized conditions was 55 000 s-1 M-1, very similar to that measured with a recombinant complex purified from eukaryotic cells. Dissociation of the NS3-NS4A complex was found to be fully reversible. No helicase activity was exhibited by the purified NS3-NS4A complex, but NS3 was fully active as a helicase upon dissociation of NS4A. On the other hand, both basal and poly(U)-induced NTPase activity and ssRNA binding activity associated with the NS3-NS4A complex were very similar to those exhibited by NS3 alone. Therefore, NS4A appears to uncouple the ATPase/ssRNA binding and RNA unwinding activities associated with NS3.

Multiple determinants influence complex formation of the hepatitis C virus NS3 protease domain with its NS4A cofactor peptide

The interaction of the hepatitis C virus (HCV) NS3 protease domain with its NS4A cofactor peptide (Pep4AK) was investigated at equilibrium and at pre-steady state under different physicochemical conditions. Equilibrium dissociation constants of the NS3-Pep4AK complex varied by several orders of magnitude depending on buffer additives. Glycerol, NaCl, detergents, and peptide substrates were found to stabilize this interaction. The extent of glycerol-induced stabilization varied in an HCV strain-dependent way with at least one determinant mapping to an NS3-NS4A interaction site. Conformational transitions affecting at least the first 18 amino acids of NS3 were the main energy barriers for both the association and the dissociation reactions of the complex. However, deletion of this N-terminal portion of the protease molecule only slightly influenced equilibrium dissociation constants determined under different physicochemical conditions. Limited proteolysis experiments coupled with mass spectrometric identification of cleavage fragments suggested a high degree of conformational flexibility affecting at least the first 21 residues of NS3. The accessibility of this region of the protease to limited chymotryptic digestion did not significantly change in any condition tested, whereas a significant reduction of chymotryptic cleavages within the NS3 core was detected under conditions of high NS3-Pep4AK complex affinity. We conclude the following: (1) The N-terminus of the NS3 protease that, according to the X-ray crystal structure, makes extensive contacts with the cofactor peptide is highly flexible in solution and contributes only marginally to the thermodynamic stability of the complex. (2) Affinity enhancement is accomplished by several factors through a general stabilization of the fold of the NS3 molecule.

[High-intensity transcranial Doppler signals in patients wearing heart valve prostheses: a prospective study]

BACKGROUND

Transcranial Doppler sonography (TCD) of the middle cerebral arteries in patients with prosthetic heart valves reveals high-intensity transient signals (HITS) and can detect asymptomatic cerebrovascular microemboli. Both the nature of the underlying embolic material (either gaseous or corpuscular) and its clinical significance remain uncertain.

METHODS

Seventy-one patients undergoing heart valve replacement (n = 63) or repair (n = 8) from June 1996 to June 1998 were prospectively evaluated preoperatively and one week, 3 months and 12 months after valve replacement using TCD. At each follow-up interval, clinical assessment was aimed at detecting neurological events. Furthermore, continuous echo-Doppler study of the carotid arteries and TCD of the middle cerebral arteries for a 30-minute period during each following visit was carried out.

RESULTS

No HITS were recorded preoperatively in any patient. At one week, HITS were detected in 25 patients (35%): 22 (65%) of these had received a mechanical prosthesis and three (10%) a bioprosthesis. No HITS were recorded in patients with mitral repair. HITS were subsequently detected only in patients with mechanical prosthesis with a positive TCD at one week, the mean number of HITS per patient being 7 +/- 18 at 3 months and 8 +/- 24 at 12 months. No neurological symptoms were evident in any patients during the postoperative evaluation. Multivariate analysis showed mechanical prosthetic valve to be the only independent predictive risk factor for HITS development.

CONCLUSIONS

The role of a mechanical prosthetic valve as a risk factor in the pathogenesis of HITS appears evident. However, HITS appear to be unrelated to possible postoperative neurological events. TCD could have more specific clinical applications if associated with methods that would make it possible to ascertain the nature of various embolic materials.

Recurrent myxoma of the left ventricle. Case report and review of the literature

A 29-year-old female was found to have a left ventricular mass while in the 14th week of gestation. Seven years earlier she had undergone removal of a left ventricular myxoma. At re-operation, after elective interruption of pregnancy, a recurrent left ventricular myxoma was successfully excised. According to a review of the literature recurrence of an isolated, localized left ventricular myxoma has not been previously reported.

[Myocardial revascularization with arterial conduits: comparison of bilateral internal mammary artery and single internal mammary artery]

The use of bilateral internal mammary artery (BIMA) grafting for myocardial revascularization has been demonstrated to provide long-term benefits compared to revascularization using single left internal mammary artery (SIMA) and venous conduits. However, it is still controversial whether the use of BIMA is associated with a higher hospital mortality and morbidity. The present study retrospectively evaluated the possible advantages related to the use of BIMA at 3-year follow-up and whether the presence of operative risk factors in patients with BIMA could limit the application of the procedure in myocardial revascularization. We compared two groups of 100 patients matched for preoperative clinical characteristics, who underwent myocardial revascularization on the left coronary system with BIMA (93 males and 7 females, mean age 59 +/- 4 years) or with SIMA and venous conduits (86 males and 14 females, mean age 63 +/- 6 years). Hospital mortality rate was 2% in both groups, the use of BIMA being not a significant risk factor for hospital mortality and morbidity. The mean follow-up was 36 +/- 6 months for the BIMA group and 40 +/- 10 months for the SIMA group. At 3 years, there was no significant differences in the actuarial freedom from cardiac death (96 +/- 2% for BIMA vs 94 +/- 2% for SIMA patients), myocardial infarction (98 +/- 2 vs 97 +/- 2%), angina (93 +/- 2 vs 91 +/- 2%), symptomatic heart failure (92 +/- 3 vs 92 +/- 2%), coronary angioplasty/reoperation (96 +/- 2 vs 97 +/- 2% ), and total cardiac events (80 +/- 4 vs 76 +/- 4%). BIMA grafting was not an independent predictor of late cardiac events. In 66 patients who underwent a late angiographic or echo-Doppler study, the patency rate was 100% for the left mammary artery, 94% for the right mammary artery and 69% for venous conduits. In conclusion, myocardial revascularization with BIMA in situ is associated with low hospital mortality and morbidity, good clinical outcome and excellent patency rate at 3 years, with apparently no significant differences when compared to the use of SIMA and venous conduits. The low hospital mortality and morbidity and the satisfactory medium-term results in our opinion justify a more extensive use of BIMA in myocardial revascularization.

Selection of functional variants of the NS3-NS4A protease of hepatitis C virus by using chimeric sindbis viruses

The NS3-NS4A serine protease of hepatitis C virus (HCV) mediates four specific cleavages of the viral polyprotein and its activity is considered essential for the biogenesis of the HCV replication machinery. Despite extensive biochemical and structural characterization, the analysis of natural variants of this enzyme has been limited by the lack of an efficient replication system for HCV in cultured cells. We have recently described the generation of chimeric HCV-Sindbis viruses whose propagation depends on the NS3-NS4A catalytic activity. NS3-NS4A gene sequences were fused to the gene coding for the Sindbis virus structural polyprotein in such a way that processing of the chimeric polyprotein, nucleocapsid assembly, and production of infectious viruses required NS3-NS4A-mediated proteolysis (G. Filocamo, L. Pacini, and G. Migliaccio, J. Virol. 71:1417-1427, 1997). Here we report the use of these chimeric viruses to select and characterize active variants of the NS3-NS4A protease. Our original chimeric viruses displayed a temperature-sensitive phenotype and formed lysis plaques much smaller than those formed by wild-type (wt) Sindbis virus. By serially passaging these chimeric viruses on BHK cells, we have selected virus variants which formed lysis plaques larger than those produced by their progenitors and produced NS3-NS4A proteins different in size and/or sequence from those of the original viruses. Characterization of the selected protease variants revealed that all of the mutated proteases still efficiently processed the chimeric polyprotein in infected cells and also cleaved an HCV substrate in vitro. One of the selected proteases was expressed in a bacterial system and showed a catalytic efficiency comparable to that of the wt recombinant protease.

Quadricuspid aortic valve

A quadricuspid aortic valve was observed in a patient requiring aortic valve replacement because of severe aortic regurgitation, while in another it was accidentally detected by means of transesophageal echocardiography performed during coronary artery bypass grafting. This report discusses the apparent rarity of this malformation and stresses the need for periodical controls in patients known to have a quadricuspid aortic valve.

Aortic valve replacement for quadricuspid aortic valve incompetence

Quadricuspid aortic valve is an uncommon cause of aortic regurgitation. We report two patients who underwent aortic valve replacement because of severe aortic incompetence; the presence of a quadricuspid aortic valve was an accidental surgical finding. In one patient the aortic valve comprised two equal-sized larger cusps and two equal-sized smaller cusps, while in the other it comprised three cusps of similar size and a small accessory cusp between the right and non-coronary cusps. This report confirms the rarity of the disease and the fact that patients with quadricuspid aortic valves characterized by cusps of different sizes are more prone to develop progressive aortic incompetence because of unequal distribution of stresses on the valve. Therefore, such patients should undergo periodic, life-time echocardiographic assessment once this malformation is detected.

Multiple enzymatic activities associated with recombinant NS3 protein of hepatitis C virus

The hepatitis C virus (HCV) nonstructural 3 protein (NS3) contains at least two domains associated with multiple enzymatic activities; a serine protease activity resides in the N-terminal one-third of the protein, whereas RNA helicase activity and RNA-stimulated nucleoside triphosphatase activity are associated with the C-terminal portion. To study the possible mutual influence of these enzymatic activities, a full-length NS3 polypeptide of 67 kDa was expressed as a nonfusion protein in Escherichia coli, purified to homogeneity, and shown to retain all three enzymatic activities. The protease activity of the full-length NS3 was strongly dependent on the activation by a synthetic peptide spanning the central hydrophobic core of the NS4A cofactor. Once complexed with the NS4A-derived peptide, the full-length NS3 protein and the isolated N-terminal protease domain cleaved synthetic peptide substrates with comparable efficiency. We show that, as in the case of the isolated protease domain, the protease activity of full-length NS3 undergoes inhibition by the N-terminal cleavage products of substrate peptides corresponding to the NS4A-NS4B and NS5A-NS5B. We have also characterized and quantified the NS3 ATPase, RNA helicase, and RNA-binding activities under optimized reaction conditions. Compared with the isolated N-terminal and C-terminal domains, recombinant full-length NS3 did not show significant differences in the three enzymatic activities analyzed in independent in vitro assays. We have further explored the possible interdependence of the NS3 N-terminal and C-terminal domains by analyzing the effect of polynucleotides on the modulation of all NS3 enzymatic functions. Our results demonstrated that the observed inhibition of the NS3 proteolytic activity by single-stranded RNA is mediated by direct interaction with the protease domain rather than with the helicase RNA-binding domain.

Enlargement of the aortic annulus with glutaraldehyde-fixed bovine pericardium during aortic valve replacement

BACKGROUND AND AIMS OF THE STUDY

Aortic valve replacement in patients with a small aortic annulus may represent a surgical challenge. We have evaluated a simplified technique to enlarge the aortic annulus which consists of extending the aortotomy incision to divide the commissure between the left and non-coronary cusps into the interleaflet triangle without opening the left atrium.

METHODS

This technique was used in 16 patients (15 women, one man; mean age 66 +/- 9 years) who underwent aortic valve replacement between August 1994 and February 1996. Aortic stenosis was the predominant valvular lesion. A mechanical prosthesis was implanted in 13 patients (81%) (21 mm in six, 23 mm in seven) while three received a bioprosthesis (21 mm in one, 23 mm in two). In all patients it was possible to insert a prosthesis at least one size larger than the original aortic annulus diameter.

RESULTS

There were no operative deaths and no late deaths. Mean follow up was 20 +/- 6 months (range: 12 to 30 months). Echocardiographic controls at 12 months postoperatively showed no evidence of periprosthetic leaks or mitral regurgitation. Comparison with preoperative data showed no significant variations of mean aortic diameter at the sinus level (30.7 +/- 2.2 mm versus 31.3 +/- 2.6 mm) or at the sinotubular junction (33.6 +/- 2.7 mm versus 34.3 +/- 2.9 mm) (p = NS). Significant reduction of left ventricular mass was observed (314 +/- 57 g versus 260 +/- 45 g; p < 0.001).

CONCLUSIONS

This technique is simple, reproducible and effective in allowing adequate enlargement of the aortic annulus and provides excellent clinical and hemodynamic results. Glutaraldehyde-fixed bovine pericardium used as a patch material showed no tendency to aneurysmal dilatation with progression of time at a maximum follow up of 30 months.

[Transmyocardial revascularization with a holmium laser: preliminary results]

BACKGROUND

Transmyocardial laser revascularization (TMLR) aims to improve perfusion of the ventricular wall via laser-created transmural channels. We present the results of TMLR with a holmium laser as sole therapy in patients with angina refractory to medical treatment and extensive coronary artery disease unsuitable for angioplasty or coronary artery by-pass grafting.

METHODS

From November 1995 to February 1997, twenty-two patients underwent isolated TMLR with a holmium laser. Five patients (23%) were female; the mean age was 67 +/- 7 years (range 53 to 74 years). Previous myocardial revascularization procedures had been performed in 17 patients (77%). Mean preoperative angina class was 3.4 +/- 0.5 and unstable angina was present in 7 patients (32%).

RESULTS

There were no hospital deaths. The only postoperative complications were transient supraventricular arrhythmias in 6 patients (27%). Each patient received a mean of 33 +/- 8 channels in 27 +/- 13 minutes. There were two late deaths, 40 days and 4 months after TMLR, due to stroke and myocardial infarction, respectively. Mean follow-up duration was 8 +/- 5 months (range 40 days-15 months). The mean number of hospitalizations due to angina fell from 4.9 +/- 1.5 in the 6 months before TMLR to 1.5 +/- 1.0 in the 6 months following surgery (p < 0.001). At follow-up, mean angina class had significantly improved (1.8 +/- 0.6, p < 0.001), as well as effort tolerance, which increased from a mean of 3.5 +/- 1.4 minutes to 5.1 +/- 1.7 minutes (p = 0.01). 201Tl SPECT at 3 and 6 months did not show any significant changes in the segmental perfusion of the lased and unlased areas.

CONCLUSIONS

TMLR with a holmium laser is a simple procedure with low operative mortality and morbidity. Short-term results confirm that clinical improvement is obtained in most patients, although this is not supported by significant changes in myocardial perfusion at short-term follow-up.